DEER ISLAND

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DEER ISLAND
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Deer Island Includes

• New sludge-to-fertilizer facility
• Primary and secondary treatment capabilities
• Inter-Island Tunnel that ties together 2 separate
  sewer systems (North and South) into one
• 9.5-mile Effluent Outfall Tunnel to discharge
  treated wastewater away from shallow Boston
  Harbor waters and into the deeper waters and
  stronger currents of Massachusetts Bay

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Deer Island Schematic

• Originates in homes, businesses, industries and
  as storm water
• Influent arrives at the plant through 4
  underground tunnels
• There are 3 main pump stations that lift the
  influent to the head of the plant
• Flows then go through primary and secondary
  treatment where the level of pollution removal is
  over 85.
• The Sludge and scum are removed
• A 9.5-mile 24-foot-diameter outfall tunnel
  transports effluent into the 100-foot deep waters
  of Massachusetts Bay.
• Effluent is discharged through more than 50
  individual diffuser pipes, each with 8 small
  ports, so that rapid and thorough mixing into
  surrounding water is achieved and water quality
  standards are not compromised by the discharge

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2002 Influent and Effluent Data

• Data provided by Charles Tyler, from MWRA, Deer
  Island Waste Water Treatment Plant
• Only the influent was used in the water balance,
  because it represents the outflow from the
  project area.

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Deer Island Influent

• Influent is normalized over LCRW
• Total inches per year 155.6 in
• Average Daily Flow 0.4 in
• Includes Wastewater from 43 communities, over 2
  million people

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Wastewater Data from MWRA

• The MWRA was able to provide us with a more
  detailed Community Wastewater Reporting System
  file.
• In order to calculate the volume of waster water
  in inches, million gallons per day was converted
  to inches-acre per day and then divided by the
  total acreage of the project area, 29,790.5
  acres.

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Calculations for Sewer and Stormwater

• Numbers had to be converted to in./day and
  normalized over the total area of the LCR
  watershed, 29,790.5 acres.
• The of each town within the project area was
  multiplied by the annual total wastewater values
• The total inch per year over the LCRW is 35.0
  inches

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Wastewater from Industries

• Over 5,500 businesses and industries contribute
  wastewater
• MWRA randomly surveys outflow of each
  business/industry
• Average Daily Discharge was calculated and
  project throughout the year.
• Total inches per year over LCRW 0.29
• Average inches per day over LCRW 0.000795

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Combined Wastewater Flows to Deer Island

• Total annual outflow to Deer Island is 35.3 in
• Average Daily outflow is 0.1 inches
• Industrial Contribution .29/35.3100 1